Jim Meyering wrote: ... > I prefer to use unsigned types when appropriate, > and adjusted a couple of other things for readability. > I'll push something like the following later today. ... > Subject: [PATCH] di-set, ino-map: adjust a type, improve readability ... > size_t h = dev; > - int i; > - for (i = 1; i < sizeof dev / sizeof h + (sizeof dev % sizeof h != 0); i++) > + unsigned int i; > + unsigned int n_words = sizeof ino / sizeof h + (sizeof ino % sizeof h != > 0);
It'd be good if I were to compile before posting a patch ;-) Those uses of "ino" should be "dev", of course. >From 8217117f3cb4ee39f8913fcfdef8b3d64dfd2437 Mon Sep 17 00:00:00 2001 From: Jim Meyering <[email protected]> Date: Wed, 7 Jul 2010 11:57:26 +0200 Subject: [PATCH] di-set, ino-map: adjust a type, improve readability * gl/lib/ino-map.c (ino_hash): Declare "i" as unsigned int. Use an intermediate variable for the for-loop upper bound, so it's a little more readable. Adjust comment. * gl/lib/di-set.c (di_ent_hash): Likewise. --- gl/lib/di-set.c | 10 ++++++---- gl/lib/ino-map.c | 10 ++++++---- 2 files changed, 12 insertions(+), 8 deletions(-) diff --git a/gl/lib/di-set.c b/gl/lib/di-set.c index ba44bcf..892950d 100644 --- a/gl/lib/di-set.c +++ b/gl/lib/di-set.c @@ -78,11 +78,13 @@ di_ent_hash (void const *x, size_t table_size) struct di_ent const *p = x; dev_t dev = p->dev; - /* Exclusive-OR the words of DEV into H. This avoids loss of info, - without using a wider % that could be quite slow. */ + /* When DEV is wider than size_t, exclusive-OR the words of DEV into H. + This avoids loss of info, without applying % to the wider type, + which could be quite slow on some systems. */ size_t h = dev; - int i; - for (i = 1; i < sizeof dev / sizeof h + (sizeof dev % sizeof h != 0); i++) + unsigned int i; + unsigned int n_words = sizeof dev / sizeof h + (sizeof dev % sizeof h != 0); + for (i = 1; i < n_words; i++) h ^= dev >> CHAR_BIT * sizeof h * i; return h % table_size; diff --git a/gl/lib/ino-map.c b/gl/lib/ino-map.c index cc9a131..f6fdd63 100644 --- a/gl/lib/ino-map.c +++ b/gl/lib/ino-map.c @@ -56,11 +56,13 @@ ino_hash (void const *x, size_t table_size) struct ino_map_ent const *p = x; ino_t ino = p->ino; - /* Exclusive-OR the words of INO into H. This avoids loss of info, - without using a wider % that could be quite slow. */ + /* When INO is wider than size_t, exclusive-OR the words of INO into H. + This avoids loss of info, without applying % to the wider type, + which could be quite slow on some systems. */ size_t h = ino; - int i; - for (i = 1; i < sizeof ino / sizeof h + (sizeof ino % sizeof h != 0); i++) + unsigned int i; + unsigned int n_words = sizeof ino / sizeof h + (sizeof ino % sizeof h != 0); + for (i = 1; i < n_words; i++) h ^= ino >> CHAR_BIT * sizeof h * i; return h % table_size; -- 1.7.2.rc1.218.gca56a
